.\" Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
.\" Copyright (C) 2000, 2001 Internet Software Consortium.
.\" 
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
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.\" 
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.\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
.\" AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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.\" PERFORMANCE OF THIS SOFTWARE.
.\"
.\" $ISC: lwres_gabn.3,v 1.16.18.11 2007/01/30 00:23:45 marka Exp $
.\"
.hy 0
.ad l
.\"     Title: lwres_gabn
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
.\"      Date: Jun 30, 2000
.\"    Manual: BIND9
.\"    Source: BIND9
.\"
.TH "LWRES_GABN" "3" "Jun 30, 2000" "BIND9" "BIND9"
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.SH "NAME"
lwres_gabnrequest_render, lwres_gabnresponse_render, lwres_gabnrequest_parse, lwres_gabnresponse_parse, lwres_gabnresponse_free, lwres_gabnrequest_free \- lightweight resolver getaddrbyname message handling
.SH "SYNOPSIS"
.nf
#include <lwres/lwres.h>
.fi
.HP 40
.BI "lwres_result_t lwres_gabnrequest_render(lwres_context_t\ *" "ctx" ", lwres_gabnrequest_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
.HP 41
.BI "lwres_result_t lwres_gabnresponse_render(lwres_context_t\ *" "ctx" ", lwres_gabnresponse_t\ *" "req" ", lwres_lwpacket_t\ *" "pkt" ", lwres_buffer_t\ *" "b" ");"
.HP 39
.BI "lwres_result_t lwres_gabnrequest_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_gabnrequest_t\ **" "structp" ");"
.HP 40
.BI "lwres_result_t lwres_gabnresponse_parse(lwres_context_t\ *" "ctx" ", lwres_buffer_t\ *" "b" ", lwres_lwpacket_t\ *" "pkt" ", lwres_gabnresponse_t\ **" "structp" ");"
.HP 29
.BI "void lwres_gabnresponse_free(lwres_context_t\ *" "ctx" ", lwres_gabnresponse_t\ **" "structp" ");"
.HP 28
.BI "void lwres_gabnrequest_free(lwres_context_t\ *" "ctx" ", lwres_gabnrequest_t\ **" "structp" ");"
.SH "DESCRIPTION"
.PP
These are low\-level routines for creating and parsing lightweight resolver name\-to\-address lookup request and response messages.
.PP
There are four main functions for the getaddrbyname opcode. One render function converts a getaddrbyname request structure \(em
\fBlwres_gabnrequest_t\fR
\(em to the lighweight resolver's canonical format. It is complemented by a parse function that converts a packet in this canonical format to a getaddrbyname request structure. Another render function converts the getaddrbyname response structure \(em
\fBlwres_gabnresponse_t\fR
\(em to the canonical format. This is complemented by a parse function which converts a packet in canonical format to a getaddrbyname response structure.
.PP
These structures are defined in
\fI<lwres/lwres.h>\fR. They are shown below.
.PP
.RS 4
.nf
#define LWRES_OPCODE_GETADDRSBYNAME     0x00010001U
.fi
.RE
.sp
.PP
.RS 4
.nf
typedef struct lwres_addr lwres_addr_t;
typedef LWRES_LIST(lwres_addr_t) lwres_addrlist_t;
.fi
.RE
.sp
.PP
.RS 4
.nf
typedef struct {
        lwres_uint32_t  flags;
        lwres_uint32_t  addrtypes;
        lwres_uint16_t  namelen;
        char           *name;
} lwres_gabnrequest_t;
.fi
.RE
.sp
.PP
.RS 4
.nf
typedef struct {
        lwres_uint32_t          flags;
        lwres_uint16_t          naliases;
        lwres_uint16_t          naddrs;
        char                   *realname;
        char                  **aliases;
        lwres_uint16_t          realnamelen;
        lwres_uint16_t         *aliaslen;
        lwres_addrlist_t        addrs;
        void                   *base;
        size_t                  baselen;
} lwres_gabnresponse_t;
.fi
.RE
.sp
.PP
\fBlwres_gabnrequest_render()\fR
uses resolver context
\fIctx\fR
to convert getaddrbyname request structure
\fIreq\fR
to canonical format. The packet header structure
\fIpkt\fR
is initialised and transferred to buffer
\fIb\fR. The contents of
\fI*req\fR
are then appended to the buffer in canonical format.
\fBlwres_gabnresponse_render()\fR
performs the same task, except it converts a getaddrbyname response structure
\fBlwres_gabnresponse_t\fR
to the lightweight resolver's canonical format.
.PP
\fBlwres_gabnrequest_parse()\fR
uses context
\fIctx\fR
to convert the contents of packet
\fIpkt\fR
to a
\fBlwres_gabnrequest_t\fR
structure. Buffer
\fIb\fR
provides space to be used for storing this structure. When the function succeeds, the resulting
\fBlwres_gabnrequest_t\fR
is made available through
\fI*structp\fR.
\fBlwres_gabnresponse_parse()\fR
offers the same semantics as
\fBlwres_gabnrequest_parse()\fR
except it yields a
\fBlwres_gabnresponse_t\fR
structure.
.PP
\fBlwres_gabnresponse_free()\fR
and
\fBlwres_gabnrequest_free()\fR
release the memory in resolver context
\fIctx\fR
that was allocated to the
\fBlwres_gabnresponse_t\fR
or
\fBlwres_gabnrequest_t\fR
structures referenced via
\fIstructp\fR. Any memory associated with ancillary buffers and strings for those structures is also discarded.
.SH "RETURN VALUES"
.PP
The getaddrbyname opcode functions
\fBlwres_gabnrequest_render()\fR,
\fBlwres_gabnresponse_render()\fR
\fBlwres_gabnrequest_parse()\fR
and
\fBlwres_gabnresponse_parse()\fR
all return
\fBLWRES_R_SUCCESS\fR
on success. They return
\fBLWRES_R_NOMEMORY\fR
if memory allocation fails.
\fBLWRES_R_UNEXPECTEDEND\fR
is returned if the available space in the buffer
\fIb\fR
is too small to accommodate the packet header or the
\fBlwres_gabnrequest_t\fR
and
\fBlwres_gabnresponse_t\fR
structures.
\fBlwres_gabnrequest_parse()\fR
and
\fBlwres_gabnresponse_parse()\fR
will return
\fBLWRES_R_UNEXPECTEDEND\fR
if the buffer is not empty after decoding the received packet. These functions will return
\fBLWRES_R_FAILURE\fR
if
pktflags
in the packet header structure
\fBlwres_lwpacket_t\fR
indicate that the packet is not a response to an earlier query.
.SH "SEE ALSO"
.PP
\fBlwres_packet\fR(3)
.SH "COPYRIGHT"
Copyright \(co 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
.br
Copyright \(co 2000, 2001 Internet Software Consortium.
.br
